build(deps): bump DavidAnson/markdownlint-cli2-action (linkerd#12403)

Bumps [DavidAnson/markdownlint-cli2-action](https://github.com/davidanson/markdownlint-cli2-action) from 15.0.0 to 16.0.0.
- [Release notes](https://github.com/davidanson/markdownlint-cli2-action/releases)
- [Commits](DavidAnson/markdownlint-cli2-action@510b996...b4c9fea)

---
updated-dependencies:
- dependency-name: DavidAnson/markdownlint-cli2-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Signed-off-by: Mark S <the@wondersmith.dev>

.github/workflows/markdown.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - uses: actions/checkout@9bb56186c3b09b4f86b1c65136769dd318469633
-      - uses: DavidAnson/markdownlint-cli2-action@510b996878fc0d1a46c8a04ec86b06dbfba09de7
+      - uses: DavidAnson/markdownlint-cli2-action@b4c9feab76d8025d1e83c653fa3990936df0e6c8
         with:
           globs: |
             **/*.md